class_docstr: Reduce learning rate in factor.
  
  Parameters
  ----------
  step: int
      Schedule learning rate after every round.
  factor: float
      Reduce learning rate factor.
code: def __init__(self, step, factor=0.1):
      super(FactorScheduler, self).__init__()
      if step < 1:
          raise ValueError(
              "Schedule step must be greater or equal than 1 round"
          )
      if factor >= 1.0:
          raise ValueError(
              "Factor must be less than 1 to make lr reduce"
          )
      self.step = step
      self.factor = factor
      self.old_lr = self.base_lr
      self.init = False
  
file_path: mxnet/python/mxnet/misc.py
imports: import math
  import logging
label_desc: Use image node_id 1 to create a new FactorScheduler object from inherited base classes: LearningRateScheduler with example: obj = FactorScheduler(step, factor)